TIRE & RIM GP 2053631 - Caterpillar

Inspect the body of transformer (3). Check that the screws (4) for ground spring (5) are tight and secure. Verify that there is no visible corrosion or damage to the transformer.
Check that the connector (7) that is for the spark plug is free of corrosion and/or for damage.
Inspect O-ring seal (9) inside extension (8) for damage.
Check for a secure connection between the transformer and the spark plug.
Check extension (8) near spacer (6) for signs of pin holes that can be caused by arcing.
The extension can be scratched and damaged with a wire brush. Do not use a wire brush on the extension.
Clean any deposits from the inside of the extension. Use a 6V-7093 Brush with isopropyl alcohol. Expected Result:The transformer is in good condition.Results:
OK - The transformer is in good condition. Proceed to Test Step 3.
Not OK - The transformer is in poor condition.Repair: The inspection found a problem with the transformer. Repair the transformer, when possible. Replace the transformer, if necessary. Be sure to use the correct transformer for the CG137 Engine.Reset the control system. Restart the engine. Clear the logged codes.STOPTest Step 3. Test the Primary Circuit and the Secondary Circuit of the Transformer
Illustration 3 g01425156
Schematic of the circuit for the ignition transformer
Measure the primary circuit by checking the voltage of the blocking diode.
Illustration 4 g01426060
Test points at the ignition transformer (partial cutaway view)
(11) Test points at the input terminals for the primary circuit
(12) Test points for the secondary circuit
Set the multimeter to the diode scale. Connect the multimeter leads to terminals (11) of the 2-pin connector. The polarity of the leads is not important. Measure the voltage between the terminals. Record the measurement.
Reverse the multimeter leads. Measure the voltage between the terminals again. Record the measurement.
Measure the resistance of the secondary circuit. Note: The resistance of the secondary coil will vary with the temperature. Illustration 5 demonstrates the relationship between the secondary coil resistance and the temperature. A reading that is within 1,000 Ohms is acceptable.
Illustration 5 g01447679
Resistance versus temperature for the 259-2078 Ignition Transformer Gp
Set the multimeter to the 40,000 Ohm scale. Connect the leads of the multimeter between test points (12). Measure the resistance between the screw for the ground spring and the connector for the spark plug. Expected Result:For the primary circuit, one of the voltage measurements is approximately 0.450 VDC. The other voltage measurement indicates an open circuit.For the secondary circuit, the resistance between the ground spring screw and the secondary terminal for the spark plug is within the acceptable tolerance.Results:
OK - All three of the measurements are correct. Proceed to Test Step 4.
Not OK - At least one of the measurements is incorrect.Repair: Ensure that the electrical power has been removed from the engine. Replace the ignition transformer. Be sure that you use the correct transformer for the CG137 Engine.STOPTest Step 4. Test the Spark Plug
Remove the electrical power from the engine.
Perform the following procedures according to the instructions in the Operation and Maintenance Manual.
Remove the spark plug from the cylinder